Resolve "Create SFG"

.gitignore

b_asic/__init__.py

b_asic/core_operations.py

b_asic/graph_component.py

b_asic/graph_id.py

b_asic/operation.py

b_asic/port.py

b_asic/signal.py

b_asic/signal_flow_graph.py

b_asic/special_operations.py

src/main.cpp

test/fixtures/operation_tree.py

test/fixtures/port.py

test/fixtures/signal.py

test/test_graph_id_generator.py

test/test_inputport.py

test/test_operation.py

test/test_outputport.py

test/test_sfg.py

test/test_signal.py